The present invention relates generally to implantable valves for use with short or long term implantable vascular access devices. More specifically, the present invention relates to a system and method for employing pressure activated valves for use with, for example, peripherally inserted central catheters (“PICC”s). Conventional vascular access devices are surgically implanted under the skin to allow for repeated access to a selected vascular structure, such as an artery or a vein, for introducing fluids to and/or withdrawing fluids from the selected vascular structure.